Is the HAT doing anything with BCM16?
Is there a schematic for the HAT out there somewhere?
With the HAT attached it appears to be affecting BCM16.
I understand BCM16 by default is pulled low by the chip and left as such as the kernel configures the device tree.
I have BCM16 connected to the base of an NPN via a 1k resistor. The base if pulled low by a 10k resistor.
The NPN turns a relay on and off.
Without the HAT all good - the pin stays low at power-up and operates normally after a GPIO config.
With the HAT, as soon as power is applied, the BCM is pulled up to 2V and the relay closes.
I can config the GPIO as an output and then set low, all good then - but something is not right.
Measuring resistance between BCM16 and GND on the HAT shows 122k - this is with everything disconnected - servos and LEDs.
Hence why I’m asking is BCM16 used for something?
I tried with BCM13 and no issues.
Removing the connection to the NPN and just measuring BCM16 with the HAT - it’s pulled up to 3.3V.
With the HAT installed does this change the device tree set-up, could it change the default setting of BCM pins, from a pull-down input to a pull-up input?
Sorry, pure amateur when it comes to the details of the device tree process.